Polyamines are organic compounds having at least two primary amine groups, for example NH2. These compounds have a role in the metabolism of mammalian cells but their exact functions are not well described. It is known that cells can synthesize polyamines and that, if cellular synthesis is blocked, exogenously supplied polyamines may be imported into the cell via the so called polyamine transporter system.
While it is known that polyamines are synthesized in cells through highly-regulated pathways, their actual function has not been fully elucidated.
They are known to bind to DNA as cations, and, in structure, they represent compounds with cations that are found at regularly-spaced intervals (unlike, say, Mg++ or Ca++, which are isolated point charges).
When synthesis of cellular polyamines is inhibited, the cell's growth is stopped or severely inhibited. Adding exogenous polyamines reactivates the growth of these cells. Most eukaryotic cells have a polyamine transporter system on their cell membrane that facilitates the intake of exogenously provided polyamines. The polyamine transporter (PAT) system is highly active in rapidly proliferating cells and is the target of some chemotherapeutics currently under development.
Polyamines are also known to modulate a number of ion channels, to enhance permeability of the blood-brain barrier and to even regulate senescence in plants, thus being considered plant hormones. Since many cancer cell lines have active polyamine transporters, it is possible to target these cells using the molecular recognition events involved in polyamine import.